i say the bolter, its your most trusted weapon and along with the trait trust your battle brother it acts like a bolt pistol with better range...
yeah other guns are better, but they dont give you as good a use for the entire squad while bolters do.

Take my love, take my land, take me to where I cannot stand; I don't care I'm still free, you can't take the sky from me.

"The difference between gods and daemons largely depends upon where one is standing at the time."- Lorgar
Member of the Fluff Masters Clan